1. Field
The present application relates generally to the operation and design of wireless devices, and more particularly, to the operation and design of power amplifiers.
2. Background
There is an increasing demand to have wireless devices capable of low power operation to provide extended talk times. One key to achieving lower power consumption is associated with the performance of the device's power amplifier (PA). For example, highly linear and efficient power amplifiers can be used to maximize the standby and talk times for a handset. However, in conventional PA designs, efficiency is generally high only at high output levels. When lower output levels are needed, typically for complex modulation like OFDM, the efficiency drops substantially.
A Doherty power amplifier has been used to improve the average power efficiency. The Doherty power amplifier has a power splitter that splits the input power into a main amplifier and an auxiliary amplifier. However, during operation when the auxiliary amplifier is not turned on, the signal power directed to it is wasted thereby reducing efficiency. Therefore, what is needed is a way to optimize the input power distribution in a Doherty amplifier, thereby utilizing all the input power which will increase the total power efficiency.